﻿/**
* @author Joey Mazzarelli
* @website http://bitbucket.org/mazzarelli/js-date/
* @website http://joey.mazzarelli.com/2008/11/25/easy-date-parsing-with-javascript/
* @copyright Joey Mazzarelli
* @license BSD license
*/

Date.fromString = (function () {

    var defaults = {
        order: 'MDY',
        strict: false
    };

    var months = ["JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG",
      "SEP", "OCT", "NOV", "DEC"];

    var abs = ["AM", "PM", "AFTERNOON", "MORNING"];

    var mark = function (str, val) {
        var lval = val.toLowerCase();
        var regex = new RegExp('^' + lval + '|(.*[^:alpha:])' + lval, 'g');
        return str.replace(regex, '$1' + val);
    };

    var normalize = function (str) {
        str = str.toLowerCase();
        str = str.replace(/[^:a-z0-9]/g, '-');
        for (var i = 0; i < months.length; i++) str = mark(str, months[i]);
        for (var i = 0; i < abs.length; i++) str = mark(str, abs[i]);
        str = str.replace(/[a-z]/g, '');
        str = str.replace(/([0-9])([A-Z])/g, '$1-$2');
        str = ('-' + str + '-').replace(/-+/g, '-');
        return str;
    };

    var find_time = function (norm) {
        var obj = { date: norm, time: '' };
        obj.time = norm.replace(
        /^.*-(\d\d?(:\d\d){1,2}(:\d\d\d)?(-(AM|PM))?)-.*$/, '$1');
        if (obj.time == obj.date)
            obj.time = norm.replace(/^.*-(\d\d?-(AM|PM))-.*$/, '$1');
        if (obj.time == obj.date) obj.time = '';
        obj.date = norm.replace(obj.time, '');
        obj.time = ('-' + obj.time + '-').replace(/-+/g, '-');
        obj.date = ('-' + obj.date + '-').replace(/-+/g, '-');
        return obj;
    };

    var find_year = function (norm) {
        var year = null;

        // Check for a 4-digit year
        year = norm.replace(/^.*-(\d\d\d\d)-.*$/, '$1');
        if (year != norm) return year; else year = null;

        // Check for a 2-digit year, over 32.
        year = norm.replace(/^.*-((3[2-9])|([4-9][0-9]))-.*$/, '$1');
        if (year != norm) return year; else year = null;

        // Day is always by month, so check for explicit months in 
        // first or third spot
        year = norm.replace(/^.*-[A-Z]{3}-\d\d?-(\d\d?)-.*$/, '$1');
        if (year != norm) return year; else year = null;
        year = norm.replace(/^.*-(\d\d?)-\d\d?-[A-Z]{3}-.*$/, '$1');
        if (year != norm) return year; else year = null;

        // If all else fails, use the setting for the position of the year.
        var pos = '$3';
        if (defaults.opts.order.charAt(0) == 'Y') pos = '$1';
        else if (defaults.opts.order.charAt(1) == 'Y') pos = '$2';
        year = norm.replace(/^.*-(\d\d?)-([A-Z]{3}|\d{1,2})-(\d\d?)-.*$/, pos);
        if (year != norm) return year; else year = null;

        return year;
    };

    var find_month = function (norm, year) {
        // Check for an explicity month
        var matches = norm.match(/[A-Z]{3}/);
        if (matches && matches.length) return matches[0];

        // Remove the year, and unless obviously wrong, use order
        // to chose which one to use for month.
        var parts = norm.replace(year + '-', '').split('-');
        if (parts.length != 4) return null;
        var order = defaults.opts.order;
        var md = order.indexOf('M') < order.indexOf('D') ? 1 : 2;
        return (parseInt(parts[md], 10) <= 12) ? parts[md] : parts[md == 1 ? 2 : 1];
    };

    var find_day = function (norm, year, month) {
        return norm.replace(year, '').replace(month, '').replace(/-/g, '');
    };

    var create_absolute = function (obj) {

        var time = obj.time.replace(/[-APM]/g, '');
        var parts = time.split(':');
        parts[1] = parts[1] || 0;
        parts[2] = parts[2] || 0;
        parts[3] = parts[3] || 0;
        var ihr = parseInt(parts[0], 10);
        if (obj.time.match(/-AM-/) && ihr == 12) parts[0] = 0;
        else if (obj.time.match(/-PM-/) && ihr < 12) parts[0] = ihr + 12;
        parts[0] = ("0" + parts[0]).substring(("0" + parts[0]).length - 2);
        parts[1] = ("0" + parts[1]).substring(("0" + parts[1]).length - 2);
        parts[2] = ("0" + parts[2]).substring(("0" + parts[2]).length - 2);
        time = parts[0] + ":" + parts[1] + ":" + parts[2];
        var millisecs = parts[3];

        var strict = defaults.opts.strict;
        if (!obj.year && !strict) obj.year = (new Date()).getFullYear();
        var year = parseInt(obj.year, 10);
        if (year < 100) {
            year += (year < 70 ? 2000 : 1900);
        }

        if (!obj.month && !strict) obj.month = (new Date()).getMonth() + 1;
        var month = String(obj.month);
        if (month.match(/[A-Z]{3}/)) {
            month = "JAN-FEB-MAR-APR-MAY-JUN-JUL-AUG-SEP-OCT-NOV-DEC-"
          .indexOf(month) / 4 + 1;
        }
        month = ("0" + month).substring(("0" + month).length - 2);
        if (!obj.day && !strict) obj.day = (new Date()).getDate();
        var day = ("0" + obj.day).substring(("0" + obj.day).length - 2);

        var date = new Date();
        date.setTime(Date.parse(year + '/' + month + '/' + day + ' ' + time));
        date.setMilliseconds(millisecs);
        return date;
    };

    var parse = function (norm) {
        return absolute(norm);
    };

    var absolute = function (norm) {
        var obj = find_time(norm);
        obj.norm = norm;
        obj.year = find_year(obj.date);
        obj.month = find_month(obj.date, obj.year);
        obj.day = find_day(obj.date, obj.year, obj.month);
        return create_absolute(obj);
    };

    return function (fuzz, opts) {
        defaults.opts = { order: defaults.order, strict: defaults.strict };
        if (opts && opts.order) defaults.opts.order = opts.order;
        if (opts && opts.strict != undefined) defaults.opts.strict = opts.strict;
        var date = parse(normalize(fuzz));
        return date;
    };

})();
